The invention relates to a device for driving a tool positioned on a pivotable part. The device comprises a combustion engine or the like and coupling means between this engine and the tool.
In one example, a pump is positioned on a ladder of a suction dredger. The ladder is pivotably mounted to the dredger vessel. The lower end of the ladder, where the pump is located, can be operated at great depths beneath the water surface. The pump serves for suction of material from beneath the water and for pumping it into the vessel or to another place.
The engine for driving the pump is typically arranged on the ladder. It is positioned at the upper end of the ladder in order to obtain, the greatest possible distance above the water surface as possible. A shaft for transmitting the power produced by the motor to the pump extends along the ladder between the motor and the pump.
Here, power transmission is effected in a direct and simple way. However operating the motor and supplying it fuel are laborious. Also, the ladder will be exposed to loads and vibrations exerted on it by the motor. The ladder will have to be designed with a view to this environment and thus be made heavier. Therefore, pivoting the ladder will require more power than optimal. It is also possible that with fierce beating of the waves, water can sweep over the motor.
Another disadvantage is that the motor experiences position changes on pivoting the ladder. Therefore, the lubrication of the motor can be endangered. This will in particular occur in larger engines, with a relatively high pump power.